Smoke alarms are generally mounted in large buildings such as residential quarters, public areas and office sites. Since smoke is generated by the burning of objects, a plurality of smoke alarms are arranged in a building according to their coverage. Smoke alarms include photoelectric smoke alarms and the like from the perspective of the sensors used, wherein such photoelectric smoke alarm is internally provided with an optical chamber consisting of a transmitter, a receiver and a chamber. The chamber consists of relatively complicated light reflecting and refracting surfaces or ribs in structure. After the unique processing of light, smoke enters this special structural cavity and the smoke density can be indicated. In the absence of smoke, the receiver can only receive a small amount of light emitted by the transmitter. When smoke enters the optical chamber, the receiver receives more light by refraction and reflection, and an intelligent alarm circuit judges whether the collected smoke density exceeds an alarm threshold, if yes, an alarm is sounded.
For the smoke normally generated in daily life, for example, smoke that will also be generated by kitchen cooking, steak grilling and barbecue, these kinds of smoke will also allow alarms to sound alarm signals, but these alarms are false alarms.